The BRMP has an ongoing study of recombinant alpha interferon in patients with hairy cell leukemia. A number of these patients have developed disease progression despite continued administration of interferon. Administration of higher doses of interferon has resulted in only minor and transient further tumor responses. This trial was designed as a salvage trial for these patients. Three patients have been admitted to this trial so far and 2 of these have achieved a partial response. All 3 patients had significant cytopenias when they started the study and all were refractory to interferon. The 2 partial responses occurred very rapidly after administration of deoxycoformycin but were associated with transient episodes of severe thrombocytopenia and febril neutropenia. One patient died after 2 doses of deoxycoformycin due to refractory and transfusion-resistant thrombocytopenia. These partial responses have been substantial with only minimal, scant hairy cells identifiable in bilateral iliac crest bone marrow biopsies. One patient with the T-gamma lymphoproliferative disorder has so far been treated on this study. This patient has not responded to date. Toxicity associated with administration of dCF has included significant myelosuppression, fatigue, nausea, and vomiting.